Ok, I understand waves and all, but for some reason I can't figure out how to manipulate the equations I know to solve these simple problems. 1. A standing sound wave in a pipe of length 2.70m is open at one end. Find the frequency of this harmonic. Use 342m/s for the speed of sound in air. 2. [a standing transverse wave on a flexible string] The string is 1.13m long with tension 10N. The total mass of the string is 8.80g. Find the period of the oscillation. 3. A typical steel B-string in a guitar resonates in its fundamental frequency at 240 Hertz. The length of the string is 0.620 m. What is the wave velocity along the string? So for number 1 I tried to use the equation f=v/wavelength . But I think I can't just use the pipe length as the wavelenth because it's not the same. But I can't seem to figure out what to do about that. For #2 I tried to use v= sqrt F/ (m/L)...but how do I get the period after solving for the velocity? I know I could use v=wavelength/T , but I don't know the wavelength... And #3, same idea. Basically for all of them I have trouble with the wavelength. Can anyone help me figure out what concept is escaping me right now? Thanks so much.